Today, machines are used for winding strand materials such as wire and cable onto reels at high speeds. Exemplary of these are those disclosed in U.S. Pat. Nos. 3,877,653 and 4,223,848 which are assigned to the assignee of the present invention. These machines have means for mounting and rotating two takeup reels side-by-side about two parallel reel axes and for alternately feeding strand material to one of the reels being rotated at high speed while the other reel is being loaded or unloaded or stationed in a standby position.
Strand takeup machines have also had means for automatically terminating the feed of strand material to the rotating reel once it has been filled and for then transferring strand feed onto the other, empty reel. This changeover apparatus, which is sometimes referred to as strand cutover, crossover or transfer apparatus, typically has a distributor through which the strand material is guided that is mounted for reciprocal movement over the reel hubs in evenly filling the reels and also for stepped movement between several specific positions over the two reels in effecting reel changeover. The changeover apparatus has further included a strand deflector arm mounted for movement between and below the two reel axes of rotation, and a snagger mounted to each reel mount adjacent one rim of each reel.
In effecting changeover an empty reel stationed aside the filling reel is first accelerated to bring the speed of its hub to the advance speed of the strand material. The distributor is then moved from a path of reciprocating travel over the entire hub of the reel being filled with strand to a path over and somewhat beyond the axis of the empty reel. At this time a shroud is moved into a position over the full reel snagger to prevent the strand from being snagged by it. The deflector arm is then moved downwardly and horizontally causing it to engage the strand material being fed from the distributor onto the filling reel and to deflect it into engagement with the snagger now rotating at high speed beside the empty reel. Once that snagger engages the strand it severs it and holds the severed strand end of the supply source to the rotating empty reel whereupon that reel now begins to fill. The shroud is then withdrawn from its position covering the full reel snagger and the full reel brought to a halt and replaced with an empty reel in anticipation of the next changeover operation.
Though high speed takeup machines of the type just described have performed well the reel changeover apparatus has not functioned as reliably as desired. Indeed, sometimes a changeover is entirely missed which forces a temporary shutdown of strand feed to the takeup machine. Since high speed takeup is often a terminal operation in a series of tandem operations performed on strand material during its manufacture, this shutdown may in turn necessitate a temporary shutdown of an entire manufacturing line.
Studies of changeover failures have revealed that improper timing related to the withdrawal of the reel shrouds during changeover is a causative factor. If the shroud is withdrawn too soon after strand severance then the strand end can fly about and become damaged or even catch on the other reel. If the shroud is withdrawn too late then convolutions of strand ballon outwardly from the full reel beneath the shroud and get caught under its lips. When the full reel is then halted and automatically replaced with an empty reel, these convolutions may break and become entangled. The broken ends may then interfere with the next crossover by striking and breaking the incoming strand. Bits and pieces of the strand material may also get caught under the snagger teeth and interfere with proper snagging of the incoming strand.